text:
What, exactly, happens when I call 1-800-WXBRIEF?
In the USA, calling the above phone number gets a pilot in contact with a flight service station (FSS). After reading the AIM and the Leidos Flight Service website, I still have some questions:

Where exactly are flight service stations, and which one does the phone number connect me to?
Is the person on the phone a meteorologist?

If not, how do they provide weather briefings?

Will someone answer 24/7 or do different stations have different hours?

Does this also apply to the FSS frequencies listed on VFR charts?

There is a list of Flight Service Stations in the US Chart Supplement.
The person on the phone is not a meteorologist and does not need to be. Though, just like pilots, they have been trained to be proficient on weather and weather related knowledge.
They provide the weather the same way a pilot can self-brief the weather. They utilize distributed briefings, Area Forecast Discussions, Prog Charts, other tools supplied to them by the NOAA, WPC, NWS, and AWC. Primary though, they use METARs, TAFs, PIREPs, and Winds Aloft reports at your airports of planned use and along your route of flight.
Someone will answer 24/7. Though, the person answering may not be from the closest FSS. It will be routed to the first available representative.
The same goes for inflight contact over VHF radio frequencies,

I see the list of Flight Service Stations in the chart supplement, but my question is about the location of each station facility itself. For instance, when I talk to Miami radio, is the person I'm speaking to actually in Miami? Or are they elsewhere in the country? Are all the operators of Miami radio in one facility? Are the operators of more than one FSS collocated in one facility?

@asb1230: many many moons ago the person on the other end of "Miami Radio" was in fact operating a radio in Miami. But in 2005 the FSSs in the Lower 48 were contracted out to Lockheed Martin and eventually all positions were consolidated into two physical locations: one in the DFW area and one near DC (I want to say Leesburg). Today the contract is held by Leidos and IIRC there is only one singular facility for the entire Lower 48. The FAA does still operate individual FSSs in Alaska.

The following FAA PDF that I found with a simple search says:

The 1-800 number appears to be an operator that will connect you to a local service station

The person giving the briefing is a certified "Air Traffic Control Specialist"

It seems 24x7, at least for Alaska

https://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/systemops/fs/alaskan/safety/Virtual_Library/media/safety-tri-fold-2012.pdf


text:
Per the AIM, Helicopter pilots may fly non-copter approaches at half the published visibility. Where is that in the FAR?
In AIM 10-1-2 Helicopter Instrument Approaches, paragraph a1 says the visibility reduction rule comes from 14 CFR Section 97.3. From what I can see, that section is just definitions. What is the AIM referencing?

Suggesting a change in question title. Question is about helicopters' provision to fly in lower visibility, but it is possible to infer something about helicopters reducing visibility around them (for example due to downwash).

I'm not sure what source you're looking at for the FARs but the reduction is indeed there in 14 CFR 97.3:

Copter procedures means helicopter procedures, with applicable minimums as prescribed in §97.35. Helicopters may also use other
procedures prescribed in subpart C of this part and may use the
Category A minimum descent altitude (MDA), or decision altitude or
decision height (DA/DH). For other than “copter-only” approaches, the
required visibility minimum for Category I approaches may be reduced
to one-half the published visibility minimum for Category A aircraft,
but in no case may it be reduced to less than one-quarter mile
prevailing visibility, or, if reported, 1,200 feet RVR. Reduction of
visibility minima on Category II instrument approach procedures is
prohibited.

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text:
Why do IFR charts show TACAN paired frequencies when there is no collocated VOR?
The image below shows a low IFR chart with a VORTAC on the right and a TACAN on the left. I understand the VORTAC is labelled with both VOR frequency and TACAN channel so that a civilian user could tune the VOR and a military user could tune the TACAN.
Why does the TACAN on the left show the frequency 112.3? I understand it's a paired VOR frequency, but if there's no VOR then why show the freq? My best guess is that perhaps a civilian user could tune 112.3 to receive DME information from the TACAN...

Your supposition is correct. Tuning the paired frequency will allow you to receive DME information from the TACAN.
If your DME tuning is through your VOR/ILS receiver, the VOR output will be flagged no computed data (NCD) as there's no VOR signal to receive.
The DME will tune the appropriate paired frequency and the DME should display normal data.
Having DME data alone is not all that helpful. However, if you have an FMS and a multi-channel DME, the FMS will tune the DMEs independent of (or in conjunction with) the VORs. This will allow the FMS to perform DME/DME navigation. That was the primary FMS navigation method until GPS came along. These days, DME/DME is a backup to GPS or GPS/IRS navigation.

Depending on the procedures around, a DME data alone (well, in conjunction with other navaids not colocated with that DME) might be helpful. Some procedures use DME arcs, DME in conjunction with NDB or ILS with non-colocated NDB. DME may also be used in defining area where circling or holding is safe and corresponding safe altitudes.

@JanHudec You are correct, but those procedures are not common. When I worked in FMS development we tested procedures that used all different combinations of navaids. Procedures that use non-colocated navaids are very rare. And those are slowly going away as they are replaced with RNP procedures.

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text:
How the stabilizer cutout switch functionality has changed from Boeing 737 NG to 737 MAX?
The Boeing 737 NG has stabilizer trim cutout switches marked as MAIN ELECT (left) and AUTOPILOT (right). Turning off the right switch disables automatic stabilizer trim in autopilot mode and automatic stabilizer trim by the STS in manual mode. The stabilizer can still be trimmed with electric trim switches on the control wheel or manually with the hand crank. Turning off the left switch disables the electric trim on the control wheel.
The Boeing 737 MAX has stabilizer cutout switches marked as PRI (left) and B/U (right).
With the MAX, Boeing added MCAS to the existing STS functionality. If Boeing kept the cutoff switches functionality intact, then turning off the right switch would disable both STS and MCAS, keeping the electric trim operable. Instead, in case of misbehaving MCAS Boeing requires to cut off BOTH switches without explaining what each of the switches does. With both switches turned off the only option to change stabilizer trim is to use a hand crank.

On the NG, if only the left switch is cut out, does it disable electric trim on the control wheel only, or it completely disables electric assist no matter where the command comes from, so in effect when the left switch is turned off it does not matter what is the position of the right switch?
What is the meaning of the new MAX labels?
What is the exact functionality of these switches individually?
Why the algorithm of turning off auto trim system has been changed?

What gets me is why you have to reach over to flip switches to disable a runaway stab.  I would've expected a disconnect button on the control wheel.

@JohnK They already have a control wheel position based cutout which is more instinctive than the switch. It also has been the same design for 61 years across every Boeing jet. The current problems have nothing to do with the cutout, but rather the identification of the issue.

@user71659 Not exactly. Even if the issue is correctly identified, MCAS cannot be cut out with the right switch only, AND it does not turn off when the yoke is pulled AND it re-engages five seconds after the electric trim switches are released. The beast can be tamed only by cutting out both switches, which leaves the pilot facing the task to manual crank the stab all the while while his mate is pulling the yoke like crazy. This is new.

@RustyCore In none of the accidents was either switch used, so that's purely conjecture. The procedure has always been to activate both switches during a runaway, so there is nothing new in that regard.

@user71659 The Ethiopian Air pilots did cut both switches, but then found to be physically impossible to hand-crank the stabilizer, so they turned the system back on to use electric trim on the control wheel. No matter the procedure, what I am asking is the specific functionality of each of the switches.

Yeah you have to unload the tail to be able to move manually, which means diving more... I was amazed to learn the '37 has a Piper Cub trim system with electric motor add-ons, but it is an early 60s design.

What do you know, I found the answer to my exact question in the Seattle Times:
First of all, even after two fatal crashes,

Boeing declined to detail the specific functionality of the two switches.

Nevertheless,

The Seattle Times found that the left switch on the 737 NG model is capable of deactivating the buttons on the yoke that pilots regularly press with their thumb to control the horizontal stabilizer. The right switch on the 737 NG is capable of deactivating just the automated controls of the stabilizer.

So far this corresponds to the information I found in the 737 NG FCOM myself.

As Boeing was transitioning from its 737 NG model to the 737 MAX, the company altered the labeling and the purpose of those two switches.
On the newer 737 MAX, according to documents reviewed by The Times, those two switches were changed to perform the same function – flipping either one of them would turn off all electric controls of the stabilizer. That means there is no longer an option to turn off automated functions – such as MCAS – without also turning off the thumb buttons the pilots would normally use to control the stabilizer.

If the above is correct, then not only MCAS, but STS/autopilot as well cannot be turned off on the MAX while keeping electric trim on the control wheel functional.

Peter Lemme, a former Boeing flight-controls engineer, said if the company had maintained the switch design from the 737 NG, Boeing could have instructed pilots after the Lion Air crash last year to simply flip the “AUTO PILOT” switch to deactivate MCAS and continue flying with the normal trim buttons on the control wheel.

(^ bold is mine). This is exactly what I was alluding to in my question. I really want to hear the reasons for the change.

Lemme said he’s surprised that Boeing made the change to take away the functionality that could have allowed the pilots to shut off MCAS without shutting off the electric switches at their thumbs.

Oops.

Avherald published an extract of the SSM for the stab cutout switches on the MAX. You can take a look

So PRI means primary and B/U backup. They just kept both switches on the panel, and reduced/converted there meaning to be a logical AND switch? I’m not a pilot, but this different kinds of abbreviations - next to each other - are confusing?


text:
What is the proper ICAO phraseology to activate a flight plan?
OK, so you have a flight plan filed (over internet, phone, company or however), go to the aircraft and get in the cockpit. So you call the controller and request IFR or VFR as appropriate.

What is the recommended wording of the request and how it is actually pronounced? Is “IFR” spelled, like “requesting eye-eff-are”, using phonetic alphabet like “requesting India Foxtrot Romeo” or expanded like “requesting instrument flight rules”?
Should you add the destination or other description of the plan? The ATC already has it, but it might serve as a check.
Do you call only when you are almost ready for start up or push back, or earlier in the preflight? And if earlier, do you also add some indication when you will be ready?

I'm asking about both VFR and IFR flight plans.

Which country are you asking about? VFR or IFR flight plans, or both?

@Pondlife, both VFR and IFR, and preferably ICAO recommended phraseology (if one exists).

Thanks for the clarification. On a related note, I once got a radio call from an airliner relaying from ATC and the pilot said that "ATC advises that the circuit at your destination is India Mike Charlie". As a student pilot I didn't catch it properly and it took me a moment to work it out; my first mental reaction was to wonder why I should care about an aircraft registered as ZS-IMC doing circuits at my destination :-)

The UK CAA Radiotelephony Manual (CAP 413, Edition 22, May 2016) has an example of how to activate a flight plan in chapter 3, section 3.36 (page 92 in the PDF).

Aircraft G-CD, departed Seton at 38 request activate flight plan
ATC G-CD, departure time 38 will activate flight plan

There is no indication whether this is for VFR or IFR flight plans, so it should apply to both if a filed flight plan wasn't activated at departure.
I also pulled out my (fairly recent) radiotelephony textbook, which covers EASA up to and including PPL including in English (and thus should be pretty close to the official ICAO phraseology), to double-check what it says. (I don't often fly with an actual flight plan active.)

Aircraft ATC callsign, aircraft callsign
ATC aircraft callsign, ATC callsign, go ahead*
Aircraft aircraft callsign, activating VFR flight plan, departed airport, hour hour minute minute, to destination airport
ATC aircraft callsign, activating VFR flight plan, hour hour minute minute
Aircraft aircraft callsign

For example, Smallprop 123 flying VFR in airspace controlled by Somewhere Control, with a previously filed but not yet activated flight plan:

Aircraft Somewhere Control, Smallprop 123
ATC Smallprop 123, Somewhere Control, go ahead*
Aircraft Smallprop 123, activating VFR flight plan, departed Hometown, one two tree five, to destination Springfield
ATC Smallprop 123, activating VFR flight plan, one two tree five
Aircraft Smallprop 123

*) the "go ahead" may be omitted
The exception to this is if you are departing from a controlled airport, in which case a flight plan filed prior to departure is activated automatically. Activating a flight plan manually is only required when departing from uncontrolled airports.
To close a flight plan, the phraseology after establishing contact with ATC is:

Aircraft Smallprop 123 position Wintermeadow closing VFR flight plan from Hometown to Springfield
ATC Smallprop 123, flight plan closed at time one tree tree zero
Aircraft Flight plan closed at time one tree tree zero, Smallprop 123

IFR / VFR are common abbreviations and therefore are pronounced eye-eff-are and vee-eff-are
The destination is usually added to cross-check that the correct flight plan is referenced
Small aircraft that do not have ground power usually call after starting the engine if possible, as you only want to turn the avionics / radios on once you have established a proper source of energy without draining the battery. If you have ground power connected or a big enough battery you might as well do so before startup (airliners get their clearance before startup, as they usually start their engines on pushback and can not simply turn their engines on and off. Also they usually have ground power or the APU running to establish a proper energy source.

"N123AB, Center, contact flight service to open your flight plan."

@Pondlife, well, they do see it, because they open it for you when you take off and close it when you land. But they don't do anything with it beyond that.


text:
Are go-arounds prohibited at St Barth (TFFJ)?
The description of this video claims that past a certain point — which is around the turn to final — on approach to TFFJ (St. Barth) runway 28, a go-around is prohibited. That sounds strange. I understand how going around might be impossible past a certain point at VNLK (Lukla) or LFLJ (Courchevel), because the hill ahead is too steep to outclimb and too close to turn away from. But while there is a small hill beyond this runway too, it should be low enough to outclimb to much further. So:

Is a go-around prohibited past a certain point on approach to TFFJ runway 28?
If yes, it is prohibited from as early as the video suggests (around final turn, still well above the hill beyond the runway)?
And if yes, what are the reasons for it?

Is there an approach chart or at least an airfield plate?

@CptReynolds, the airport even has scheduled service, so there should be, but I can't find it.

He’s talking about the VFR pattern for Rwy 28.  Yes some airports, due to terrain or other obstacles do have points where by normal procedures, are one way in past certain points in the approach.  If you do a lot of mountain flying, you’ll find that’s the case with a lot of remote airstrips.  Courchevel in the French Alps is another airport with a one-way-in-only final approach.  Gustaf III is considered one of the most difficult and demanding airports to land at and I know requires special training for approval to land there.  It does however allow for a Go-Around up until passing Eden Rock, so you better be stabilized and on airspeed prior to that.  Once past that, you are committed to landing.

you are committed to landing.... or crashing


text:
Who controls VFR flights in class B airspace in Europe?
I was reading about this incident where a near miss occurred in class B airspace between IFR and VFR flights that were in contact with different controllers.
So I would like to know which controller normally gives the clearance to enter class B airspace to a VFR flight? When entering from class E, does the area controller provide the clearance or the approach controller of the airport whose class B it is? And is the flight then handed off to the appropriate approach controller? And when the aircraft then crosses from one class B airspace to another?
That particular incident happened

at 4000 ft amsl. This chart does not list frequency for that airspace, but it is clearly airspace of the (Danish) Kobenhavn/Kastrup (EKCH) airport. But it is in Swedish airspace and Sweden area (ESAA). The VFR flight was flying from east to west, so must have crossed from other class B sector that apparently belongs to Malmo (ESMS) about 5 nm earlier. So does it make any sense it was (still) talking to Swedish controller (the article is not absolutely clear, but seems to say it was Sweden area, not Malmo approach) while the other flight was talking to Kobenhavn approach?
Obviously I am not trying to find what happened; the investigation will hopefully eventually explain that. I'd just like to understand what the normal procedure in such situation is.

It's class C not class B, according to this part of Swedish AIP describing parts of Swedish national airspace where ATC is delegated to Denmark; see area L2. Class B is not used in Denmark at all. (Not that this matters much because class C does require a working mode A+C transponder as well as ATC clearance for VFR).

@HenningMakholm: Hm, I just assumed the skyvector chart is consistent and blue borders always mark class B while class C would be purple.

SkyVector charts are based on the old ONC "1 mill" charts, which use blue lines for ALL types of airspace. You are making assumptions based on US Sectional charts, but these are NOT Us Sectionals.

@RAC, I am pretty sure skyvector was (I don't see it there anymore) showing a key somewhere with those symbols somewhere, though they never applied outside USA.

The airspace in which the mentioned incident took place is not classified B. In fact, no class B airspace exists in Denmark or Sweden at all.
The incident did take place in København TMA (which is airspace class C).

So I would like to know which controller normally gives the clearance to enter class B airspace to a VFR flight?

I don't know how this works in the USA, but in most of the world, it is very easy to figure out which ATC unit is responsible for a specific airspace. All aerodrome specific airspaces, such as control zones, are listed in the appropriate AD 2 section of the AIP. For all other airspaces, including TMA's, you should look at the ENR 2.1 section of the AIP.
If you look up the airspace in question in AIP Denmark, you will see that the responsible ATC unit is Copenhagen APP, specifically the approach east sector (118.450 MHz). So, the specific unit who will give clearances to enter this specific airspace is Copenhagen Approach. There is no general answer to your question, since different procedures are used in different places.

When entering from class E, does the area controller provide the clearance or the approach controller of the airport whose class B it is?

There is no class E airspace to be found around the position of the incident. Plenty of G, though.
The ATC unit responsible for providing service in a certain airspace is the only unit who can give a clearance to enter such airspace. In the specific case, Copenhagen Approach is (naturally) the only unit which can issue a clearance into its airspace. If such a clearance is received by another ATS unit, it has been initially provided by Copenhagen Approach and then forwarded to another unit to pass on to the pilot.

And when the aircraft then crosses from one class B airspace to another?

Again, I think you are assuming that every part of the world works like the USA, which is not the case. What I think you mean is: What happens when an aircraft crosses from one TMA to another? And what you really should be asking is: What happens when an aircraft crosses from one ATC unit area of responsibility to another?
The answer to which is quite simple: the aircraft will be transferred to the next ATC unit, who will then provide appropriate service within its airspace.

So does it make any sense it was (still) talking to Swedish controller (the article is not absolutely clear, but seems to say it was Sweden area, not Malmo approach) while the other flight was talking to Kobenhavn approach?

København TMA - airspace class C - extends from various lower levels to FL195. At the position of the incident, as you have indicated on the chart, the TMA extends from 2500 FT upwards. While Copenhagen Approach provides service within København TMA, service in the airspace below the TMA (which is classified G) is not provided by Copenhagen Approach. Unlike other Danish airports, where the local approach unit will provide service "in, above, below and around" the TMA, Copenhagen Approach is simply too busy dealing with IFR traffic to and from EKCH. Service to traffic below the TMA (which is mainly VFR traffic) is thus provided partly by Malmö ACC (Sweden Control), partly by Copenhagen FIS (Copenhagen Information).
As it so happens, service within Malmö TMA (which is class C, rather than class B as you suggest) is also provided by Sweden Control. There is no approach unit at ESMS - approach control service is provided by Malmö ACC. Therefore, it makes perfect sense that the pilot, coming from the east, was talking to Sweden Control. And since the controllers on the Sweden Control sector had no reason to assume otherwise, they had to believe that the VFR flight in question was in fact below København TMA, in class G airspace, where Copenhagen Approach does not provide service. This is of course not true - the VFR flight was actually in København TMA, for reasons which are beyond the scope of this to discuss - and as such, should have been talking to Copenhagen Approach (and should have been operating a mode C transponder).
At the same time, the IFR arrival (737) was approaching EKCH, within København TMA (class C), and so, was correctly talking to Copenhagen Approach.
What happened then can be read from the incident report. My purpose with this was simply to clear up the misunderstanding concering the airspace in question (which is also what the original question was about).

Thanks for clearing things up. My confusion with class B comes from the fact that skyvector uses the symbols it normally uses for that class and the map key does not explain the regional differences.

I can definitely see where the confusion comes from. As far as I can tell, Skyvector does not even provide a chart legend/key for areas outside of the US (which I find rather odd!). For someone not familiar with the airspace, that makes their charts more or less useless. Anyway, I'm glad I could clear things up. In case you were looking for a good VFR chat of the area, one is available here: http://aim.naviair.dk/AIM%20Documents/VFR%20Flight%20Guide%20Danmark/VFG%20Part%204%20-%20KORT/EK_Chart_ANC_COPENHAGEN_AREA_en.pdf

I'm assuming you're referring to this where a Cessna 172 had a near miss with a 737: http://www.havarikommissionen.dk/~/media/Files/Havarikommissionen/Havarirapporter/Luftfart%202014/Preliminary%20ATI%20Bulletin%20HCLJ510_2014_273.ashx
Regarding who the VFR pilot should have been talking to, that depends. For example if you're flying in Los Angeles you might get clearance into the bravo for LAX from SoCal Approach if you're taking the "coastal route" through the bravo, or you might get clearance from LAX tower if you're flying the lower altitude "mini route" which directly overfly's LAX runways and tower and you'd be talking to whoever you got clearance from until they handed you off.
It really depends how they've set it up. The  terminal area chart (TAC chart) for the bravo airspace contains VFR flyways and procedures including who to contact for clearance. So if you're interested you can get the TAC chart for Kobenhavn and look (usually) on the back of the physical chart where it has more info.
However, having said that: I think this VFR pilot accidentally flew into bravo airspace and will probably lose his/her license. Here's why:

Pilot did not have a Mode C altitude reporting transponder which is REQUIRED to fly in to Bravo.

From the report:

Aircraft B was reported to fly at 4000 feet with no radar presented altitude readout.

I'm not sure how "Sweden control" hands off to Denmark, but if he's flying to bravo in Denmark you'd expect him to be talking to someone in Denmark, either the bravo airport's tower or Copenhagen Approach which is who the Boeing 737 involved in the incident was talking to.
If he was in Bravo legally he should have been assigned an altitude, heading and squawk code and ATC should have maintained separation between those two aircraft and the bravo controllers are the best in the world at doing exactly that. So I think he accidentally flew into bravo and was talking to the wrong controller.
Edited: To remove irrelevant detail about VFR altitudes above 3000ft AGL.

Is the Mode C required in Bravo everywhere or only some countries (including USA)? Because this aircraft clearly flew through lot of Bravo before the incident. Surely if it was a requirement, the controller would have chased him below the floor of the Bravo segment (on SkyVector it looks like he was in Bravo throughout the flight and while it would be possible to fly just below (MSA 1300, Bravo floor 1500) except both his departure and destination airports are Bravo too).

I think you are making too many assumptions about the cause and speculate about the possible consequences for the pilot involved. The report say there was no radar presented altitude readout. The cause could be either on the transponder side or on the surveillance ground system side. Even if it were on the transponder side, there's no evidence that it was caused by the pilot. I don't know how the Swedish CAA deals with such cases but revoking a license without evidence of misconduct or gross negligence by the pilot seems unlikely to me.

@JanHudec Which controller? Sweden? Which likely doesn't control that bravo.

@DeltaLima If you're suggesting ATC's mode C transponder receiver may have been inoperative, that would have been made very public because it's a potential disaster for bravo airspace.

@seattle272SP I am not suggesting anything, I try not to jump to conclusions prematurely. This aircraft is from 1970, the transponder could be as well. It would not be the first time that an old transponder does not reply to the perfect shaped pulses from a modern Mode A/C/S interrogator while it is responding to interrogations from older Mode A/C radars. There is a long chain of technology between the altimeter and the controller's display. Drawing the conclusion that the pilots license is going to be revoked because of missing Mode C indication is premature.

@DeltaLima: If the transponder was working and problem was on radar side, there would have been a TCAS RA (in the B737) and that would almost certainly be mentioned in the incident (as it would look very different). So it is almost certain that the Cessna did not transpond in mode C.

@JanHudec I think that is a fair assumption. Let's see what the final report brings.

Agreed with the comments about the pilot losing his cert: we should avoid speculation. Especially because busting class B, at least in the US, is not typically grounds for revocation. Remedial training, yes. 509 ride, perhaps. Revocation? Probably unlikely.

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text:
Does EASA allow using a portable GPS for RNAV capability?
Assume an older IFR-certified aircraft with the classical equipment, that is two VOR/ILS receivers with plain CDIs, ADF and DME, but no GPS. It can be flown IFR, but many routes can't be used, because they use fixes that can't be found with this simple equipment.
If a suitable portable (that is, not built in nor connected to the aircraft systems) GPS unit is available in cockpit, and has appropriate aviation maps loaded, it it allowed to plan or accept an RNAV route that can only be flown using the GPS? What features and certifications does the GPS unit need to be usable this way?
Note that I am not thinking about any RNP procedure nor a RNAV approach (the ILS is there for approach in IMC), just normal en-route navigation over fixes defined by coordinates only. That way, the GPS is not critical—if it fails, I can always request vectors or rerouting over a navaid.
(If it differs over the world, I am most interested in European situation)

Is the GPS rigidly mounted or hand-held?  Either way, I doubt it will be allowed to be used for any safety-related function.

The key point may be whether or not it is hard-wired into the aircraft's electrical system.

It is definitely not wired into anything in the aircraft. It is mounted so that it does not get flung around in case of turbulence, but only so that it can be brought into the aircraft before flight and removed again after landing.

@JanHudec Im trying to find the exact reference but under the FAA I belive to be legal for RNAV routes (and approaches) the GPS needs to be panel mounted.

Although you're asking about EASA, you can also see this question for the US rules

The answer, broadly is no, handheld GPS units can not be used for IFR RNAV routes (or approaches for that matter). To know if a specific GPS unit is legal for IFR navigation you need to check up on a variety of paperwork, thats covered in this answer. Strictly speaking if you could find a certified unit it would be legal but there are no current units (to my knowledge or searching) that are.
If we look at the regulations and bounce around a bit we can see why. AC 90-108 tells us about the use of RNAV systems and states that one must be compliant with installation instructions in AC 10-138D of which there are many different regulations. The AC does not actually specifically state that the unit must be panel mounted but in a round about way it does:
The definition of display which is used widely in the document does state it must be mounted to the panel,

Display. Within the context of this AC, a display is a device mounted
in the aircraft instrument panel to convey course guidance navigation
information to the aircrew for controlling the aircraft along the
intended route. Displays may also be used to convey other information
as well.

There are also lots of regulations about wire mounting to avoid issues and failures as well as other mounting regs. If you are interested its worth going through the document.
See Pondlife's comment bellow for more info on panel mounted GPS'

just normal en-route navigation over fixes defined by coordinates
only. That way, the GPS is not critical—if it fails, I can always
request vectors or rerouting over a navaid.

In order for the GPS to be non critical you must fly at altitudes serviced by other nav-aids. The reason GPS routes are coming into use is that they, in some cases, allow flying at lower altitudes that may be beneath ATC radar or out of range of nav-aid coverage. In the case of a failure of a GPS unit you would then be with no means of navigation and terrain avoidance.

See this answer for a more explicit FAA reference on panel mounting.


text:
Are modern fighter jets allowed to fly with an inoperative ejection seat?
I'm wondering if a modern fighter jet (Eurofighter, JAS Gripen, F-35 etc.) is allowed to fly when the ejection seats are known not to be in working order.

As a side note, ejection seats are very, very dangerous things, so it would almost certainly depend on what isn't working about it.

That will vary very much from country to country. While civil aviation regulations are very much standardised across the globe through ICAO (of course with local exceptions) and manufacturer's guidance, military aviation is very much the domain of national regulations.
Technically a military jet will be able to fly with an unserviceable ejection seat, so I imagine that some countries under some circumstances allow flying when they don't work.

you are right.  I would further add that the military also differentiates between peacetime missions and combat missions.  Even back in WWII engines had a "War Emergency Power" setting, primarily relating to the boost pressure on turbo- or superchargers.

Summary
If the ejection seat is inoperable on a US military aircraft, the aircraft will be grounded 100% of the time.  I'm sure you could come up with some weird hypothetical "end-of-the-world" scenario where you'd still take off, but that isn't reality today.
F/A 18 E/F Checklist Procedures
Interior Checklist
After strapping into the jet, the ejection seat is the first thing you check:

Leads, leg restraints, and harness - SECURE/ADJUST
Ejection control handle - CLEAR
Ejection control handle pin - VERIFY REMOVED

There's no point in removing the pin and checking the handle if you do not intend to arm the seats.  This is further confirmed later in the checklist.
Before Takeoff Checklist

[...]
Harness - ATTACHED 8 POINTS
[...]
Seats - ARMED IN THE FRONT
(2 seater) EJECT SEL - ARMED, AFT INITIATE

If the seats aren't armed, then the jet is never leaving the ground.  It is potentially suicidal for fighter aircraft to takeoff without ejection seats.  Fighters don't glide well (they fly to the scene of the crash), they can't fly in a total electrical failure, some can't fly without computer guidance, they can't fly with hydraulic failures, and they fly in very adverse flight conditions.  There are a lot of things, that if totally failed, would turn a fighter into a flying coffin, sans ejection seat.  Fortunately these systems are very redundant, but its usually not worth staking your life on it.

Hmm; In theory I can just go buy a MiG and bring it over, but I'm not sure it's legal for me to own an ejection seat.

This is the correct answer.  The accepted answer pales in comparison, and is fundamentally incorrect.

I asked some of the fighter pilots that I know, and they couldn't give me a concrete answer (for the USAF), and I couldn't find a regulation that states it is grounding. However, I'm  sure it would ground the aircraft.
In this instance, fighter jets (F-35s) were grounded for a "relatively" minor issue with the seat:

Fifteen F-35 Joint Strike Fighters will remain grounded for at least five more days because their ejection seat parachutes were installed backwards
...
Even though the parachute was packed backwards, it still would have deployed, but the steering levels on the parachute would have been reversed, making it confusing for a pilot to steer

Key note there is confusing for the pilot. The ejection seat was functional, but the fact that it was confusing was enough for it to be grounding. Possibly in wartime it would have been different, but I doubt it.
And even in the case that it wasn't grounding, there's no way I (or any of the pilots I talked to) would take that aircraft. It's not worth it.

It makes good sense to ground the planes in that situation during peacetime. On the other hand, one assumes a different attitude would have been taken if the US was at war and a squadron of enemy bombers heading straight for DC.

It would obviously depend on the situation, but the probability of there being few fighter jets not grounded in the region around DC where they would need this one jet without the ejection seat is pretty low. There are lots of jets there, not to mention air to air missiles. And there would probably be plenty of warning - they can change out a whole ejection seat pretty quick.

And I can fully imagine the aircraft being ferried to a central repair/maintenance facility for repairs rather than a team with their gear being shipped out to a forward base, especially if it's a single aircraft and the repairs would require a lot of people or equipment.

Maybe in rare cases. But I've seen them change out the seats. A new seat only requires some simple tools and a small hoist to get it into the plane-all of that gear could fold up and be carried in one medium sized truck,  or two humvees

I thought I would add a relevant incident happening now in 2022.
Hundreds of USAF aircraft, including the F-35, and an undisclosed number of US Navy aircraft are grounded due to "ejection seat safety concerns". The cause is a defect in cartridge devices that deploy the parachute when the pilot pulls the ejection handle.
Here is a link to one of many news stories covering this:
https://www.businessinsider.com/usaf-f-35s-join-planes-grounded-ejection-seat-safety-2022-7
It also appears this same issue has grounded a number of RAF Typhoons. It is interesting to note that the RAF is only halting "non-essential" flights while the USAF grounded all possibly affected aircraft.
Here is a link to an article about the RAF grounding Typhoons:
https://ukdefencejournal.org.uk/raf-halt-non-essential-typhoon-flights-due-to-issue/
This gives further evidence that modern fighter jets are almost certainly grounded when ejection seat issues arise. However, this incident also shows that how these issues are handled varies by defense force.

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


text:
What regulations apply to flying near blasting areas in Canada?
I was flying near CYPK the other day and for convenience and since I was close to it, reported as being "above the blasting area". My instructor pointed out better not to do that. That made me think about the legality of flying above a blasting area but I couldn't find anything about that, neither in the AIM, nor in the CAR.
On my VTA a blasting area is shown as a "striped circle", similar to a circular special use airspace. The CFS legend for that symbol says "CAUTION BLASTING AREA. Do not overfly at less than 3000' AGL". The CFS entry for Pitt Meadows CYPK says "Quarry blasting ops ... to 300 AGL".
Obviously it's a good idea to stay away from a blasting area and having read a bit about it since then, I won't fly over it below ~3500' in the future. For closure and future reference I would like to know:
What are the Canadian regulations around flying over/near blasting areas?

Does the CFS actually say 3000' AGL, or AMSL? I would think it would have to be an impressive blast to be a threat to aircraft 3000' above the ground.

Blasting areas are not subject to particular regulation, they can be depicted on charts and/or announced by NOTAMs (code for blasting is WH, compliant to ICAO standard).
The blaster operator always ensures the area is clear of traffic prior to firing. The imminent blast may also be announced 4 and 1 minute(s) prior to the operation on 123.2 MHz. In case an aircraft is seen, the blaster operator will also use this frequency to inform the pilot of the blasting operation. See below for details.
It's pilot responsibility to remain clear of these areas:

Source: AIP Canada

Known permanent blasting activities can be depicted on VFR charts and announced by NOTAM until charts can be updated. From AIP Canada:

The “VFR Chart Updating Data” section of the CFS provides a means of
notifying VFR chart users of significant aeronautical information to
update the current VFR aeronautical charts. In this regard,
significant  aeronautical information is considered to be that which
affects the safety of VFR operation, e.g. obstructions, restricted
and advisory areas, blasting operations, cable crossings, and new or
revised control zones. New or  revised information of this nature,
which is required to be depicted on visual charts, is advertised by
NOTAM  until such time as the information can be published in the “VFR
Chart Updating Data” section of the CFS.  Subsequently, the NOTAM is
cancelled.

However temporary or itinerant blasting activities may not be advertised. From the Canadian AIM:

Another  concern  to  low  flying  is  the  blasting  operations
associated with the logging industry. The trajectory of debris  from
the blasting varies with the type of explosives, substance  being
excavated and the canopy of trees, if any. These blasting  activities
may or may not be advertised by NOTAM.

More details are given in the NOTAM Operating Procedures, chapter 5.5.5:

In the Pacific Region, NOTAM are not issued for blasting related to
logging activities under the following circumstances:

If using instantaneous blasting equipment.(The blasters will ensure the area is clear of all air traffic prior to the blast.)

If using a standard 6 minute-fuse and using aeronautical frequency radio. (The blasting operator will make two transmissions on 123.2 MHz
advising of the imminent blast. These transmissions will be at
approximately 4 minutes and 1 minute prior to the estimated blast.
These transmissions will include the geographical location referenced
to prominent landmark and the time to the blast.)

If blasters detect an aircraft in the immediate vicinity of a blast,
they will direct a radio transmission to that aircraft using aircraft
type and colour ("Red and white helicopter, you are over an active
blast site; clear the area immediately.").
Blasters may elect to use both methods for added safety.
A NOTAM will be required if the blast site is within 5 nautical miles
of an aerodrome or if the blaster elects not to use either of the
above procedures. In any case, the NOTAM will have a maximum duration
period of 14 days.

Minimum safe altitudes don't take blast risk into account. From the Canada Air Pilot publication:

"CYA, CYR and known blasting areas are not considered in the
establishment of MSA altitudes. For this reason, it is the pilot’s
responsibility to remain clear of these areas as applicable"

Source: Canada Air Pilot
More: See this discussion: Quarry blasting not regulated for aviation safety purposes.

"CYA... remain clear of these areas". Frankly, that sounds like good advice! :)


text:
Do logged hours really reflect ability?
I was recently flying with an ex commercial pilot. He told me that the only person he'd flown with that was worse at maintaining a heading was another ex A320 pilot with 20k+ hours. His reasoning was that both him and I watch SkyDemon instead of picking a point on the horizon.
It got me thinking, for commercial pilots, do total hours really reflect the pilots skill level?
Take Bob and Barry:

First Officer Bob flies an A320 and does the same 30 minute domestic route every day. He averages 8 take-offs and landings a day and has 2000 hours logged.
Barry is a captain with 20,000 hours logged, also flies an A320 and only does long haul flights averaging 13 hours each way. He performs an average of 1 take-off and landing per day.

If total hours aren't the best measure of skill, what other metrics might best reflect a pilot's skill level?

I seem to remember that skill fade of long haul pilot is an often studied area of flight safety. I'll find some links.

@Bianfable NO that does not - I'm not asking what hours can be logged, I'm aware of that. I'm specifically asking about how to measure pilot skill. I have edited the question

Thanks @Jamiec - as I have added to the question, it would be useful for others I think to state what metrics ARE a good determinant of skill level.

what do flight hours matter if one is a child of the magenta line?

Probably there is no metric (or an opaque one). Hours is one, but landing are also a different metric (short haul pilots may get more experience on the most difficult part of flight (under 10 000 feet). Night, instrumental, busy spaces, etc. And most important ability is about dealing with emergencies (so commercial pilots with flight simulators and training are best suited with emergencies)

Competence is directly related to the size of a certain organ which is directly related to hours logged.  How do you not know this?

Are you talking about basic flying skill or command skill, which encompasses a zillion variables beyond stick and rudder?

Total hours is a good measure of skill, but perhaps not the best measure of skill. That is usually attributed to hours on type. Also important to note that, at least for this answer, I'm conflating "skill" with "lack of accidents". That's not necessarily a good measure of skill.
Back in 2013, Aviation Safety magazine posted a good piece on exactly this subject. Some relevant excerpts:

In 2010, 96 percent of the 1500 civilian aircraft accidents in the U.S. involved general aviation. According to the NTSB’s 2010 Annual Review of Civilian Aircraft Accident Data, the average pilot pursuing personal flying and who was involved in an accident had a “total flight time of 2863 total hours, with a range of 20 to 31,270 hours. The average time in the type of accident aircraft was 460 hours, with a range of 1 to 10,000 hours.”
Anybody with even a modest grounding in statistics can see a standard deviation and data variance big enough to fly a Twin Beech through.

So clearly, pilots of all skill levels measured by "total hours" have accidents.

A 2002 epidemiological study of airline pilots by researchers at Johns Hopkins University found experience, measured by total flight time, offered a significant protective effect. With adjustment for age, Part 121 airline pilots with 5000 to 10,000 hours had a 57-percent lower risk of a crash than pilots with less than 5000 hours

Total flight time shows significant reduction in accident rates, however insurance rates tell the real story, as these are the people who have actuarial reasons to calculate risk factors.

Based on writings and policies of the aviation insurance industry, pilot experience in a specific aircraft make and model is considered a better measure of competency than total flight time. Insurance underwriters can favorably rank a 1000-hour pilot with 500 hours in the make and model with a 10,000-hour pilot who has no make and model experience.

I would add to this that these metrics are used partly because there really isn’t a great way to measure skill directly in an objective manner. It’s the same general issue that you run into with almost any large complicated skill-based task that can’t be trivially automated (because if it can be trivially automated, you know exactly what skill is needed).

Hours equate to experiencing a range of different scenarios and possible outcomes.  Undoubtedly, there is learning that has taken place to mold the airman into the pilot they are today.  Some of the only correct thought processes can be achieved through experience.
You might remember the saying.
There are old pilots and they are bold pilots but there are no old, bold pilots.
Older pilots, through experience, have learned more thoroughly what it means to stay safe in many different situations.

With that said, I don't necessarily think flight hours are a good barometer for pilot skill.  I have seen and trained pilots who were phenomenal at 500 hrs total time and I have seen pilots who could barely pass a checkride with 10,000 hours.

Checkride pass/fail rates are better determining factor on pilot skill.  It is only by observation that one can assess pilot skill.  There are numerous industry evaluators trained to assess such things.
I would look at checkride pass/fail rates for each pilot.  I would also drill down to the specific make and model checkrides to determine competence in a specific airplane.

Small airplane pilots are required to have a flight review every two years.  How long did the ground session take and how long and how many flights did it take to receive a sign-off?

Part 121 and 135 as well as multi-crew airplanes (61.58) require a checkride every year.  What were the results of those checking events?


text:
Should I telephone tower to tell them I'm alive?
Yesterday I had a somewhat stressful flight out of a busy airport back to my local airfield.

After take-off the navigation "equipment" (a tablet) failed, the controller asked me for my position around a mile out, my response was incorrect as I was trying to troubleshoot the device, so he gave me a few Visual Reference Points to help out.
About 8 miles out, I saw a wall of fog & rain closing in from the left of my heading, it was coming in fast, went all the way to the ground and was certainly IFR (I was on VFR and am not instrument rated). I called the controller and asked about the weather, he said there had been unexpected reports of IFR conditions and not to succumb to get-there-itis. He suggested returning, which I declined for now.
Due to these distractions, I had stopped climbing, the controller called me to ask me to verify my altitude as there was high terrain around me, for which I was too low.
Shortly after this I encountered moderate turbulence.
The controller then called me to say we were going to lose two-way communication soon, he got weather for my arrival destination and asked me to switch to London frequency as he didn't want me not talking to anyone (I wasn't anywhere near London by the way).

At this point, my brain became overwhelmed and I was unable to think clearly, I didn't change frequency, I did land safely but after landing realized I hadn't performed some of the pre-landing checklist items and had also gone the WRONG WAY around the circuit before landing (luckily no one was around).
In these kinds of situations, should you telephone the departure tower to tell them you arrived safely, or is that just extra noise they don't need?

Just a note "London Information" is not London as in the city, its London Centre - goes all the way from the mid channel to the north of england, and Irish sea out to the north sea.

High terrain... were you in the Lake District or Wales or something?

You always close the plan, don't see why you wouldn't in a situation where tower has reason to fear the worst?

@JohnK mountains around the Cotswolds@Gier there was no FP filed

If you were a close and treasured friend of mine, and you told me all the above, I would have an honest talk with you about the possibility of maybe not piloting any longer, or at least without much, much more training.  So many red flags.  I have only admiration and great respect for people who realize that it is best for them to stop flying/driving/skydiving/etc.

I'd say "** the navigation "equipment" (a tablet)**" is a backup navigation equipment at best; you should be able to fly without it, too.

YES, please call and let them know. Especially because you had been instructed to change to another frequency and you did not. Even without that, it sounds like the controller knew you were "in distress" (at least mentally, if not mechanically). Letting them know you arrived safely will be a relief for them.

And it lets them know not to call search-and-rescue to look for your crashed airplane.

If the controller files safety reports, or even if he doesn't, it would be a good thing to call and give some details as to how you arrived safely. You may be providing some bit of information that the controller can use to help the next pilot who encounters a risky situation.

I don't think so; I mean, it's not necessary. You might want to phone and thank them for helping you out when you were in a stressful situation, but remember that's their actual job, not some sort of heroics.
It sounds like you had an eventful flight, and one where maybe you learned two things:

You're a recreational flyer. If the weather looks suboptimal, go another day. But;
Even in marginal weather conditions, you could handle it and although you may chose next time to stay put, your training took over and you dealt with things as they arose.

Don’t beat yourself up too much for forgetting some landing checks. It happens. It's best if it doesn't, but I can honestly say that I've done the same loads of times, often when it’s a clear calm day and I should not have made simple mistakes.
Don’t beat yourself up for messing up the circuit either. If nobody else was around, no harm, no foul. The important thing was you landed safely and can fly another day.

Thanks for the encouraging words Jamie, was certainly disappointing, but as you say, it could have been much worse

Even though it's part of their actual job to deal with stressful situations, the air traffic controllers are human too. They do care a lot about the safety of those flying in their airspace and feel a great personal responsibility.  I am very sure they sometimes worry about the good outcome if they lose radio contact, even if that loss of contact is expected due to terrain. I'd say, give them a call. It certainly doesn't hurt.

@DeltaLima Yes, I admit I missed the part about not changing frequency when asked to. I'm surprised that didnt generate a DnD flag or two TBH.

@Jamiec perhaps the aircraft was still within surveillance coverage so they knew it was still flying. I am doing a (side-) project to see if I can supply a FIS unit with supplemental (non-ATC- approved) surveillance data to reduce the number of unnecessary SAR dispatches and have FIS staff less worrying about the outcome of lost flights by letting them know that the missing aircraft is still moving.

@Jamiec this answer makes more sense to me, but since the other one has more votes, I'll go ahead an accept that one (FYI I did give them a call and they seemed to appreciate it, although it clearly wasn't NEEDED)

@Cloud cool. Note I didnt say you shouldn't call, just that you needn't.

As someone who used to coordinate SAR activities at my facility, I would have been looking for you or your wreckage. I have talked to many spouses in the middle of the night asking if the have heard from the pilot. In the US, simultaneous unexpected loss of radar/radio contact is treated as an accident.


text:
Yet another "Why aren't I soloing yet?" scenario
Undoubtedly this question has been asked many times, but perhaps my situation is a little different than others. I'll try to be detailed but succinct:
I've accrued about 18.5 hours, 17.5 under the same CFI. I've checked off the 3 nighttime hour requirement (although my CFI said before my checkride we'll do more to get my nighttime pilotage skills improved), and 2 of the 3 required hours of XC, plus about one hour instrument time. Over the course of all this training time I've accrued 90 landings (my CFI loves touch and goes and we can do 10 landings in little over an hour). Yet still I'm not ready to solo. Now, I know I'm not the most proficient pilot he's seen, and perhaps I'm just average among the overall population, but 90 landings, and not including the hundreds of landings I've done on my simulator and countless hours around the patterns of my local airfield? Rarely do I have a hard(er) landing and some downright kiss that runway on or near centerline. Here's the other compilcation: My CFI is a one-man shop with his own planes, has logged 18,000 hours in his career and is a lifelong instructor, about 29 years experience as a CFI. If my CFI was part of some instructor mill at a flight school, I would certainly consider walking away or having a serious discussion with him at this juncture. However, since I respect his seniority it's creating a lot of cognitive dissonance. Am I missing something? Another little twist: he says I'm on a trajectory to be one of his 45 hour and done students (he has numerous students done in under 50 hours and an extremely low failure rate), so perhaps he's one of those people who solo people later after making sure things are absolutely positively perfect? Has anyone had an instructor who went about the process in this manner?

I understand the need to vent, but there really isn't an un-opinionated answer to this question. You really should be discussing this with your CFI.

Understood. I modified the end of my question to see if other pilots had a similar experience with an overly conservative instructor.

Just dug out my log book, 83 take-offs and landings before my first solo.  Dunno if that's typical.  Also, my opinion of my flying ability at that point was probably not the same as my FI!!!

I know people who haven't solo'd until well into the 30's. They aren't bad pilots or slow learners, it's just about comfort levels and even things like insurance requirements. Some instructors just wait longer as a matter of personal preference.

I soloed in 10 hours in 1975 but I was 18 years old and the syllabus was about 2/3rds of the modern one.  I would say most people solo between 15 and 30 hours; the older you are the longer it tends to take.  I used to instruct at a summer glider camp where we would take on 15 teens all at once and bring them to license in 2 weeks, and even with all youngsters the variation was astounding, ranging from "top gun" boys who soloed almost right away to stragglers who had to come back after the camp to finish up their training.

Welcome to aviation.SE! Because this is a Q&A site, not a discussion forum, we expect questions to be specific and clearly answerable. Your question is a good one, but it just isn't a good fit for this site: we prefer to avoid questions that ask for opinions and suggestions. If you're new to StackExchange, the [tour] may be helpful.

This question is pretty open ended.  As a CFI myself, I really couldn’t assess whether you are ready to solo or not until I have flown with you and seen how you are handling the airplane on takeoff, landing, and in the traffic pattern.
My general assessment standard for readiness to solo is to see the student exhibit solid knowledge and practical fundamentals for takeoffs and landings and the required airmanship needed to perform them down pat.  They can either correct for errors in the approach and landing or exercise good judgment when a go around should be executed.  Very rarely, if ever, do I need to provide technique guidance, verbally or otherwise.  The student may not yet be acceptable quality for a checkride, but the technique is solid, safe and the student is exercising sound judgment in ADM and risk management for airport operations, including go-around assessment and techniques, pattern spacing, accounting for the effects of wind, solid crosswind skills in light winds.
First off, we want you, the student, to be safe.  The last thing I want as a CFI is to grab a newspaper or turn on my TV and see an airplane crash in the news with my student’s name listed as a casualty.  Secondly the CFI is legally responsible for whatever you do on a solo flight he/she has authorized and their ticket can be on the line if anything happens and the authorities determine they are culpable.  We don’t want you guys going out and breaking the law, unintentionally or otherwise.  Third, we don’t want you to learn and ingrain any bad flying habits and techniques, particularly when sending you out on your own, so it’s best - and particularly during the pre-solo phase - that we route them out early.
Finally, everybody is in a rush to get the magic minimum number of hours to go for a checkride.  Or solo.  Or go on a cross country, etc.  We all have heard stories about people going from no experience to PPL in two weeks (drunks at a bar tell fanciful tales, too, BTW!).  We all expect to do this or better because every pilot thinks he/she is Sierra Hotel and wants to be better than the other guy.  While I can appreciate this, especially from a financial standpoint, keep in mind that that’s just the MINIMUM seasoning the FAA expects in an applicant.  Typically people are getting a PPL these days at around 70 or so total flight hours.  While the regulations provide guidelines for what an knowledge and practical skills an applicant should bring with them for a checkride, solo or any other phase of their flight training, the real answer is are they unconsciously competent at their airmanship to do it.  Like any human endeavor which requires motor control and practice we have good days and bad ones.  When your ‘bad day’ in the airplane is at or above the standards set for that phase of flight training, be it solo, checkride, or otherwise, you’re probably ready to pass.
I hope that helps.

A nicer answer than mine, so I tip my cap to you.

You aren't soloing because your instructor wants you to live a long and happy life.
Instructors who are allowed to sign you off as safe to solo have your life in their hands, and potentially the lives of others in the future.  If you aren't ready in the estimation of the instructor who signs you off safe for solo, you aren't ready.
Keep trying, keep learning, keep getting better, keep working.  You'll get there.
Your instructor wants you to come back alive.  So do I.
Just so you know: over 2,000 hours as instructor in my log book.  (And that's not a lot compared to career CFI's, I am sure Carlo has a lot more than me).

Landing counts show experience, but are you ready to take control of the plane?  Do you have it broken down to where you are comfortable to fly the plane without intervention
through the entire pattern?
In any learning (even after age 50), you basicly fill your brain with information and apply it
to your task.  Eventually it comes "naturally", but not before a period of confusion, bewilderment, and doubt.
Everyone is different, so pressuring your self to solo after X number of landings only
leads to more stress.  It sounds like your instructor thinks you are doing well, but sometimes
even very experienced people can just gloss over things that may be very important to you.
So now you are at the point where it might be a good idea to talk to the mighty king and say
YOU want to fly the plane, if you feel you are ready.  Try a few circuits as if he is not there,
and explain this is important to you.
I would not worry about his feelings too much.  My instructor saved me from crashing
twice, but later the parts began to fit.  All the parts, not just I landed.


text:
Why don't big commercial planes have full aircraft parachutes?
On smaller aircraft, like some Cirruses for example, they have parachutes attached to the body of the aircraft that can help the plane get to the ground safely in an emergency.
I'm wondering why commercial aircraft (like, say, a Boeing 737 or Airbus A320) don't do this?  I figure it might have to do with the speed a jet moves at, or maybe the altitude, but I was hoping to get a more complete answer by posting the question here...

In short, having this kind of a parachute for a 737 or an A320 is not impossible as a concept, but would be too expensive, too heavy, too impractical, too difficult to implement, and hardly ever used.

@usernumber I wonder though... fire extinguishers are also hardly used and yet they have them.  So where exactly is the place where cost, usefulness and safety all converge?  And how close to that point would a system like this be?

The "break apart" portion of the other question is really a small part of it. Most of the responses discuss general disadvantages of parachutes and apply to the intact case as well. I'd like to see this edited something like "what are the advantages of keeping an aircraft intact under a parachute", if that is what you want to focus on.

I think this is unnecessarily splitting hairs.  The intent of the questions is different, and a google searcher looking at both questions, I think, would feel the same.  That's mainly my argument here, the questions themselves are different regardless of the information found in the answers of the either question.

Are there other practical means of 'slowing' down an aircraft, other than parachutes?

I think a company that produce aircraft would profit hugely if they could sell more secure planes :) It only takes one accident to make people wary and damage the reputation of a company

@Freedom Er, no. Rather, companies already make astoundingly safe planes; there is virtually no edge to be gained in the airliner market with safety, because safety is already regulated well past the point where there are relevant differences between aircraft. And large airliners are pretty much a duopoly, with aircraft purchasers knowing that aircraft are all incredibly safe as a prerequisite to sale and that accidents at some level are inevitable, so there's not really that reputation thing.

@Firee Yes. Pitch up.

There's also the safety hazard of an inadvertent deployment of parachutes midflight.

I read something, wish I could remember where, that stated large commercial jets design would ultimately have to defer to one of two guiding principles; make them better at not falling out the sky or make them 'crash better'. The former was given prominence as 'a better way to go'.  Can't remember the justification.

"there is virtually no edge to be gained in the airliner market with safety" - airplanes are not 100% safe. if someone knows their life could be saved if they payed more, that's potentially a huge selling point. also, expensive safety designs will eventually go down in cost. but as i read the answers below i see your point too.
(apologies if it's against the rules to critique comments).

The reason for not using full aircraft parachutes can be stitched together by looking at the many related questions. Let me do this for you:

Parachutes will only help when something essential fails at sufficient altitude for parachute deployment. As paul said here, most accidents happen at take-off and landing where a parachute cannot be successfully deployed.
Parachutes big enough to slow down a whole airliner will be very heavy, reducing payload and increasing the number of flights to transport the same number of passengers. The biggest parachutes designed so far were for the solid rocket boosters of the Shuttle, and paul gave their mass a 3 x 990 kg plus 550 kg for the drogue chute. Wikipedia gives the mass of one SRB at 91,000 kg. Scale this for the zero-fuel mass of an A-320 of 62,500 kg, and the mass will be approx. 2,500 kg. That is equivalent to 25 passengers, or 16% of the A-320's capacity. Adding the parachute will translate into 16% more flights, just to compensate for parachute mass. This is most likely underestimating the true impact because I did not add the mass for structural reinforcements.
The opening shock at travel speed would destroy both airplane and chutes. If we want the parachute system to work in as many cases as possible, we need to make deployment possible at up to Mach 0.85, and then the maximum g-load on aircraft and passengers must not exceed 6 g. (See here for Eiband diagrams which give time- and direction-dependent limits for the maximum deceleration a human being can survive). This is possible with staggered deployment of several chutes with increasing size, and by sewing parts of the canopy and the parachute's strings together, so they can rip apart during opening, which slows the unfolding process. But I expect that this will add to the mass of the parachute system. It will certainly add to the mass of the aircraft's structure, which is currently limited to +2.5 / -1.0 g.

By looking at point 2 above alone, it becomes clear that the addition of parachutes will most likely drive up air travel casualties. If we need 16% more flights to make the cruise part less dangerous, and still most accidents happen during take-off and landing (which are now 16% more numerous), we gain little. Crashes now involve fewer passengers, but their number goes up. Tickets will become 20% more expensive at least (more if the parachute system costs something, which is very likely), and we all know how the majority of passengers votes when faced with a choice of dearer, somewhat safer flights and 20% cheaper flights at almost the same accident risk.

Did the SRBs even touch down at a vertical speed that would be reasonably survivable for passengers in an aircraft cabin? And what would the plane's attitude be during descent? Dangling from attachment points at the rear, with everybody inside dangling from their seatbelts?

@HenningMakholm: Good point, but I left it out because I have no information on the sink speed of the SRBs on their parachutes. Since they were designed to land in water, I would expect that the sink speed is too high to be safe for an airliner. The attitude should be similar to flight, maybe with a 20° nose down angle. Throw in a roll angle so one wing touches the ground first and helps to brake the impact of the fuselage.

I'd like to add a 4th point: Once parachutes are deployed, you lose most if not all ability to control where the plane goes. The plane will be subject to the prevailing wind condition.

@Jason: Correct, but the same is true when the aircraft comes down uncontrollably, but without a chute. Deploying the chute will greatly reduce the impact energy, regardless where it comes down, so this is not a clear disadvantage in my eyes.

@PeterKämpf: Your point is valid. My bias comes from flying in Southern California where you are always pretty close to mountainous terrain. Many SR pilots have said deploying the parachute is not an option for them for fearing drifting into terrain.

I am sure, future aircrafts would be designed from scratch to have this kind of facility inbuilt..

There is also the matter of when a parachute system should be deployed. The captain would have to be in control of the trigger, and would have to decide that deployment is the best option in a given situation. Seems unlikely to me that it would ever happen. Either the aircraft would be flyable and could be landed successfully, even without engine power, or successful deployment would be impossible for some reason - whatever makes the aircraft unflyable would likely make the parachute system either unusable or its deployment destructive to the rest of the aircraft.

I suspect the 16% more flights would simply be addressed by operating larger aircraft, at least on the routes served by A320s. Your point is none-the-less valid on routes already served by the likes of the A380.

So an empty A320 is lighter than an empty Space Shuttle SRB?  I never knew that!

@Jason: Still better than crashing into said terrain.

@Sean, that's precisely the reason many pilots don't like the parachute system. Once the parachute is deployed, you may crash into unfavorable terrain without any say. (Context: this sentiment is common among pilots in  Southern California where the terrain is more of an issue). At the end of the day, it's a personal choice and preference. No right or wrong.

Ironically, passengers don't have to choose between cost and safety. The safest airlines statistically speaking are the budget ones!

One final point would be that, on a multi engine aircraft, you really don’t need the parachute - you can always land on one engine.

Another factor is trans-oceanic flights; even if the passengers survive the landing and escape from the aircraft, they are unlikely to survive until they are rescued.

So these are all valid points, I just struggle with the 700+ people that died last year with the 737 Max planes without control and a parachute would have saved all their lives. You can design for xyz contingency as you should all the time and airline manufactures do. The problem is there is always a problem and going back to basics would have saved lives. Will there be a plan crash in 2020? Absolutely. Would have it been survivable with a space age material lighter than the ones posted in this answer, probably yes.

@KevinParker So you expect an aircraft manufacturer who leaves critical input to a flakey and non-redundant sensor to fit a humongous parachute to their planes? It would had been much cheaper and had cost much less additional mass to fit an adequate horizontal stabilizer. But that costs money … oh, by the way, those parachutes also don't exactly come for free. You cannot fix a rotten culture with technology.

Yes, because I hear that all the time Peter. Flight 102, flight 610, flight 58 yes yes would have been fixed had there been one more sensor, one more line of software code or one more safety feature that the airline didn't order. It's getting old and people are dead year after year. Sometime this year an engine will explode in a way it shouldn't have because of some unforeseen problem like a loose screw, weak glue, welding problem, metal fatigue blah blah and everyone on the plan would have prayed to whatever got they weren't so cheap and delusional about their safety there was a parachute.

@KevinParker: Now suppose that parachute has been added. On deployment, it is torn to pieces because the manufacturer was too cheap to use decent materials. Will you now ask for a second, redundant parachute or shouldn't we really address the core of the problem?

Peter - No one said anything about a second parachute just you. Just like they have backup hydraulics or electrical power, redundant systems help make flying safer.

All very interesting. I would have made the arguments around a) horizontal velocity, which would somehow be reduced to 0 prior to touch-down, b) balancing the aircraft so that it doesn't crash people face down into the ground and c) Parachute landings are not really soft and smooth, the tin can would still smash into the ground and today is certainly not built to do that and keep passengers safe. Planes that can reliably do a) and b) after a successful lift off are hardly in a situation where they need a parachute to land. More so if they can do c) as well.

Any time the question is "why don't we have...", the answer is almost certainly in the trade-off between weight, maintenance cost, fuel cost, & utility. If it weighs a lot, needs maintenance, burns fuel, and will only be useful once a decade, then it just is not productive.
Putting a complex parachute system on a plane will be heavy, meaning fewer passengers, or less fuel or cargo on board. All that extra weight has to be flown around, requiring fuel. They would need regular maintenance checks, which is another cost. And a parachute would only be useful very, very infrequently (on most planes, it would never be used).
So it is just impossible to justify adding new equipment for a once-in-a-lifetime scenario, which can be better managed with good maintenance, good training, and good planning.
This same line of reasoning goes for "why don't more airplanes have rocket thrusters", "why don't planes have anti-missile systems", "why don't planes have airbags", and many other random items.

Your remark is basically inherent to the question.  I'm aware there is a trade off, I want to know what form it takes.  Mostly I'm curious about why it might weigh so much, or if it might pose particular structural and aerodynamic issues.  What causes this solution to be impractical in particular, basically.  Dismisses it as "simply a trade off" kind of misses the deeper purpose of the question.

As others have already pointed out, such measures are counter-productive.  They would kill more pax than they would save by putting a greater number of aircraft through flight phases where accidents are more likely.


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Is public data available for routes that enter/exit a certain airspace?
I'm interested in air traffic density and flux (i.e., traffic that enters and exits) for the ZLA airspace. A good first pass would be flights that begin or end in ZLA (and that data is pretty easy to get from somewhere like OpenFlights, but that doesn't include routes like PHX-SEA, where a flight would pass through ZLA on its way from ZAB to ZSE. Is there any public information available about what routes pass through ZLA?
(Actually, I'm much more interested in the air traffic density and flux specifically for the Los Angeles metropolitan area, but I figure starting at the area control center level might be a good place to start.)

Related http://aviation.stackexchange.com/q/12375/6886. You may find the answers there helpful.

@digitgopher they definitely were! It got me started but ultimately did not address my question.

A free public resource would be the FAA's statistics page. I'm not sure if they have the specifics you need but they have a lot of data available. It would probably be easier to find data specific to the airports than it would for the whole artcc. Flight data doesn't usually include what airspace they pass through but where they depart and arrive.
There are commercial sites that have the raw data. FlightAware has full xml data for pretty much all scheduled flights going back several years. It's a treasure trove of data, it's a matter of extracting it. If you can write an api then  have options for using their data for a per-query fee. Their info page is here Their prices are in fractions of a penny, but I really know nothing about api's so I have no idea how quickly they would add up. It probably depends on how efficient the api is in getting the information with the least number of queries.


text:
Why do airports have to close in bad weather?

Shouldn't aircraft be able to withstand winds of up to 100 mph? When flying the wind is at a much higher speed than that.
Shouldn't they be able to take-off through fog using instruments alone?
Shouldn't they be able to take-off on a slippery runway, since the wheels are not powered.

One point that answers have not yet addressed is the requirement to brake in the case of an aborted take-off.

Adding to what the others have mentioned, bad weather is often a combination of low visibility, low ceilings, precipitation, high winds and lightning.
Visibility and ceilings
As mentioned in @fooot's answer, ILS is available to land when in these conditions.  Every airliner and crew (and just about every airport they'd go into) is trained and equipped for ILS operations.  A standard ILS approach is good in weather down to 200 ft ceilings and 1800 or 2400 ft visibility along the runway (RVR).  Further airplane and airport equipment and aircrew training can allow ILS category II and III operations, which reduce these numbers (cat II is 100 ft vertical visibility and RVR 1200, cat III goes down to essentially no visibility).
To takeoff, a 2 engined airliner needs 5000 ft RVR (1 mile vis) normally.  Airport lighting and airline opspecs can reduce this as low as RVR 300.
Wind
High winds are fine, but can make the landing more challenging.  When the winds are strong and particularly gusty, a lower flap setting can be used to land and a faster approach speed flown.  This will, however, necessitate a long landing rollout.  Exceptional crosswinds can also present problems aligning the aircraft with the runway, and if you can't line up, you can't land (note that some larger airplanes can land in a crab and do not need to align with the runway until the main gear are on the ground).
Runway condition
You mention the wheels are not powered, and this is true.  However, the friction between the runway and the contact patch on the tire is the only thing keeping the airplane on the runway in strong crosswinds, so you need friction to land (or takeoff) if there is a crosswind component.
Anything reducing friction is problematic (rain, snow, ice, rubber, etc),  With high water you risk hydroplaning and this (or snow/ice) can lead to departures from the runway sides or an overrun if braking action is insufficient due to lack of friction.  Ice needs to be chemically treated and snow must either be treated or plowed at regular intervals (while it is snowing). Ground handlers at the airport must also have deice fluid and the equipment to apply it to aircraft available for operations in snow.
Lightning
When lightning is in the vicinity, ground crews go inside as it is a deadly hazard to be on the ramp in those conditions.
Summary
All of these things contribute to lowered arrival rates into the airport and as conditions deteriorate you reach a point where you are spending more time dealing with keeping the airport open than departing airplanes and it makes sense to close the airport temporarily.

you mean aircraf must carry deice fluid to operate?

@vasin1987 No, either the airport, airline or FBO will take care of deice fluid and application.

Well, the runway condition paragraph confuseme a bit :)

@vasin1987 the airport is responsible for keeping the runways maintained so that aircraft can operate on them.

Wind
The problem with wind is that it can be from any direction, not necessarily the direction of the runway. When the wind is coming from the side instead of straight ahead, it is called a crosswind. This means that landing aircraft have to point into the wind to remain lined up with the runway. The slower they are flying, the further to the side they must point the nose. Airliners are designed to land in these conditions, but it requires more skill to do it well. The control inputs required to compensate for a crosswind affect aircraft on takeoff as well, as then must work harder to stay lined up with the runway and stay level through lifting off. High winds tend to come along with gusts, which makes it even harder to control an aircraft. Aircraft during flight are flying faster, so changes in wind are less problematic. Once they are flying slower, the wind is much larger compared to the aircraft's speed, and control is much more critical during landing. Aircraft have crosswind limits, and even below those limits, aircraft may need to go around from a landing attempt, which introduces delays.
Another issue is wind shear, which is when the direction and/or speed of the wind quickly changes. A change of 40 knots at higher speeds is turbulence. During landing or takeoff, it can cause the aircraft to stall and crash.
Visibility
Aircraft can certainly use systems like ILS that allow them to take off or land in low visibility. However, there are many limitations with these systems. The crew must be trained to use them, the aircraft must be equipped to use them, and the airport must be equipped with them. However, when the pilots are relying on instruments, they no longer are able to see hazards like usual. Because of this, separation requirements are inreased in these conditions, which means an airport can't handle as much traffic.
Water
It's true that aircraft wheels are not directly powered. However, traction is still very important during braking, since aircraft can hydroplane just like a car can. This means aircraft need more distance to stop, and can slide off the runway if they lose traction. Frozen water in the form of ice or snow makes a plane even more difficult to steer or stop.

Combine all of the above (a typical storm that would cause delays at an airport), and you can see why airports delay flights or close when conditions get worse.

Also note the effects of snow, ice, and rain.  Too much snow/ice on the wings, and your airplane will crash into the Potomac (real case).  Too much snow on the runway, and you might not be able to gain flying speed.  Icy or wet runway, crosswinds could push you off the runway before you're going fast enough to have control authority.  I believe a really heavy rain could even stall the engines, though the only cases I recall involved flying into thunderstorms.  And so on.  The point is, why take the risk?

Keep in mind that airports typically never close, at least not due to weather. Airlines can cancel flights and pilots can choose not to land/takeoff from an airport, but the airports themselves usually never close due to weather. Controllers can make advisories saying that aircraft might not want to land at an airport, but they can't directly stop flights from landing at the airport.

Add to all this that even if the visibility goes to 0 and/or ceiling comes down to ground level, you can still take off (talking about the USA) if you are flying Part 91 (set of laws to fly by). It is everything but safe though, and in an emergency you will probably not make it back safe.
Systems like ILS or VOR approaches have limitations. The ILS usually requires you to see the runway environment (FAR §91.275) 250ft AGL, so you need to have some kind of minimum visibility/ceiling above AGL to land!

The wind should be coming from the right direction and be reasonably steady. Gusting crosswind is a very dangerous thing.
Also it's not just the planes that need to be out in the cold wind but also the ground crew, if you force them to work in such condition you will get unions on your doorstep, unions.
On takeoff you need to maintain the center line, if you deviate a bit the plane will plough into the grass next to it and you will not be flying today.

In order:

If the wind were exactly aligned with the runway this might be theoretically possible.  Maybe.  But, the wind never directly lines up with the runway, and a 100mph crosswind would blow the airplane right off the runway before it ever got off the ground, causing it to crash.
They can, though it's better if you can at least see the runway lights.  What is actually impossible is taxiing, there's no system that allows you to follow taxiways to the terminals with no visibility.
Again, yes, they can use the runway so they can take off.  But, when they land, they do use their brakes to stop.  If their tires get no grip, the planes would generally slide off the runway (an no, engine braking is not powerful enough to stop a plane on their own.)  So having no traction on the runway may not stop you from taking off, but it will stop you from landing.

These are some of several reasons weather can shut down an airport, though there are several more.  You might considering asking about other conditions in separate questions though.

To point #2, airports with SMCGS installations and low visibility taxi plans can handle ground movements in extremely low visibility.

@casey huh, didn't know.  I need to ask a question about that.  Is this commonly installed on planes and commonly had at airports?

There is no airplane installation, just charts for the taxi plans. It is common at large airports (nothing too special, just taxi routes with high intensity centerline lights and various other lights). In general it is likely found at any airports that do low visibility ops (rvr300/500/600/1000 takeoffs and cat II and III landings).

Just because you can take off on a runway isn't good enough. In an emergency, you may need to return to the airport. If the conditions at the airport aren't also safe for landing, then you won't be allowed to take off.

Wind

Shouldn't aircraft be able to withstand winds of up to 100 mph?

Can the airframe withstand it? Sure. They deal with twice that in the jet stream almost daily. Can they land or take off in it? Not so much, especially if the wind is not straight down the runway (which it almost never is.) Every aircraft has a maximum crosswind component in which it can complete a safe takeoff or landing roll. I'm not aware of any of them near the 100 mph figure. What happens when you try to take off with a crosswind component that is too high? Well, possibly something like Continental Airlines Flight 1404, which got blown off the side of the runway on takeoff in Denver after it had already accelerated above 100 knots. Everyone survived, but the Captain as well as another person sustain critical injuries and the aircraft was destroyed.
The worst part about winds from storms, though, is that they tend to be very gusty with rapid changes in both magnitude and direction. Say you're flying a final approach and you suddenly encounter a 50 knot tail wind. Your wings just stalled and, if you're low enough and/or the gust lasts long enough, you just crashed short of the runway. Also, sudden changes in crosswinds can cause runway excursions.
Thunderstorms are also capable of producing a nasty type of sudden downdraft called a microburst. These are particularly nasty to encounter at low altitude. As you approach a microburst, it causes you to have a sudden strong headwind (and, thus, higher airspeed,) which suddenly increases the lift of the wings, while also slowing down the ground speed of the aircraft. Pilots may naturally compensate for the increased airspeed by reducing power. This then becomes a huge problem seconds later when that headwind vanishes and the wind is instead pushing the aircraft straight downward, causing it to lose altitude quickly. To make a bad problem worse, as the aircraft flies out of the microburst, it now has a sudden tailwind, which quickly decreases the airspeed, causing the wings to produce significantly less lift and perhaps even stall. Encountering such a microburst on short final to DFW near a thunderstorm caused the crash of Delta Air Lines Flight 191 in 1985, one of the most deadly aviation accidents in U.S. history.
Visibility

Shouldn't they be able to take off through fog using instruments alone?

Sure. They do it all the time (in the case of airliners, at least.) Visual flight rules are not allowed in fog, but all airliner flights use instrument flight rules anyway. Sometimes they execute visual approaches, but nearly every airport that handles airliners and all airliners and airline flight crews have the ability to perform an instrument landing. Many commercial airport runways (and most airliners) are equipped and certified for fully automated landings. Takeoff doesn't even need that.
General Aviation is another matter here, though. Pilots and/or aircraft not certified for instrument flight rules cannot operate in fog. While many GA pilots and aircraft are certified for IFR, many also aren't. Flights not using IFR must be operated under Visual Meteorological Conditions, which generally require that aircraft can only land or take off when the cloud ceiling is more than 1,000 feet above the ground level and horizontal visibility is at least 3 statute miles (at least in the U.S.)
Traction

Shouldn't they be able to take-off on a slippery runway, since the wheels are not powered?

Not really, no. The big problem here is not the lack of ability to accelerate with the wheels, but rather the lack of directional control and the inability to brake. On both takeoff and landing, the aircraft relies on the contact of the landing gear with the pavement to maintain directional control. Also, traction is also obviously required to use the wheel brakes (which provide the primary stopping force on airliners.) Ice is particularly nasty about causing loss of directional control on the runway. For example, Tower Air Flight 41, a 747 departing JFK for Miami, lost directional control on takeoff due to ice, resulting in a runway excursion. There were no fatalities, unless you count the 747 itself, which was damaged beyond repair.

If 100 miles an hour generates enough lift for the aircraft to fly, then a wind gusting 100 miles per hour might result in the aircraft taking off while the passengers are still climbing the steps.
Kites fly without any speed relative to the ground.  When the wind blows strong enough, so do aircraft.  In weather like this the aircraft are either secured to the ground with tie-downs or taken indoors.
(Not that tie-downs always work.)

While a PA-28 can fly at 100 mph (or 45 mph, for that matter,) almost no airliners can. I believe most airliners will have stall speeds above that, even when empty with full flaps. That picture is definitely a good illustration of what wind can do to a light aircraft, though.

"Ugh... what did I do last night?"

If you look at historical behavior, you'll find that airports in the 1970s and 1980s generally didn't close for bad weather. Stapleton Airport in Denver for example, never closed for weather a single time until a major blizzard in 1982.
I believe the reason they do now is liability law. Though they could theoretically continue to operate in most bad weather with a 99% chance of safety, that 1% chance of having an accident and facing an expensive lawsuit from injured passengers or surviving families causes them to err on the side of caution.

Can you please add a reference about Stapleton Airport not closing because of weather until 1982?

There are many articles about the blizzard of 1982, which I'm confident was the first full weather closure of Stapleton, but I can't seem to locate any articles that specifically mention that fact. http://www.nytimes.com/1982/12/28/us/snow-glogged-denver-area-bracing-for-new-storm-and-colder-weather.html

All of the comments about weather describe why the pilot of an aircraft might not want to land when certain phenomena are present. But this does not mean the airport is closed!.
Airports themselves "close" very very rarely. When they do it is almost always because there is some problem with the runways. Most often this is contamination from snow and ice, which reduces traction (and therefore braking action) to unsafe levels that preclude any aircraft operation whatsoever. Other issues could include damage to the runway, a disabled aircraft on the runway, or in the case of grass strips a runway that is too waterlogged to safely support an aircraft.

For almost all other meteorological phenomena, the airport is still technically "open" and available for a pilot to use if they desire; it is up to the pilots themselves to determine if they feel comfortable using the airport for departure or landing. Sometimes there are regulations (such as 14 CFR 121.651) that dictate certain weather minima, and sometimes an air carrier's Operations Specification (which is a pre-approved document that is binding on the pilots) may dictate even more conservative minima, but this does not mean that the airport is closed.
Ceiling and visibility conditions could be so bad that pilots cannot visually acquire the runway environment and therefore are unable to continue to land, but this does not mean that the airport is closed. Some aircraft and air carriers are certified to conduct "zero/zero" landings, and others are not.
Air traffic control can enforce a ground stop to an airport, meaning that flights bound to that airport are not issued takeoff clearances, often due to unsustainable volume (amount of inbound flights); the volume is often unsustainable due to poor weather resulting in more spacing required on final and more go-arounds, but could be because of other reasons like higher-than-usual demand (such as all the private flights going to Florida around the holidays). But this still does not mean that the airport is closed. An aircraft in distress would still be allowed to attempt an approach.

A point to bear in mind with all of these, is that it doesn't take much for flight cancellations if your airport is already running very close to capacity with no time to makeup earlier delays.
This notably is the case with Heathrow where NATS (UK ATC) will be trialling time based separation over the current distance based separation between aircraft. Here's a good explanation from them about the impact of headwinds on landing rates and how measures like this can mitigate some of these impacts: http://www.nats.aero/tbs/

"trialling" -- never knew this was a word.  Guess they verbed a noun once again.  Well, I'm going to go airplaning now, bye bye.  PS https://www.grammarphobia.com/blog/2017/11/trial.html

All of these questions answer from the point of view of the plane. Can it land, can it take off, can the pilots see, can they control the plane, etc. But there is another aspect not yet mentioned: ground staff.
It's incredibly common for long delays to be caused by thunderstorms because it's not safe for anyone to be outside during active lightning. This means the people who hold the sticks to show the planes where to park, the people who hook up the fuel trucks, the luggage handlers - dozens of people many of whom are handling dangerous equipment, and all of whom have to stay inside until the lightning stops. An airport may stop allowing landings and takeoffs even when the planes would have no trouble landing or taking off because it's not safe for ground crew to be out there.

Multiple answers mentioned this already. They were posted the same day the question was asked, over 9 months ago. Don't resurrect old questions if you're not adding something new.

Also, this factor doesn't technically close the airport, just the ramp. Aircraft which have already pushed back can still take off in lightning and arriving aircraft can still land. They just can't push back a departing aircraft or dock an arriving one until the lightning stops. I suppose powerback is possible in this scenario if they've already undocked the jet bridge, disconnected ground power/air, and removed the chocks, though.

@nobody -- I only see one existing answer mentioning lightning -- this one https://aviation.stackexchange.com/a/12624/34686 --

Worrying about lightning harming ground crew on the ramp area seems unrealistic to me -- I mean it's one thing if you are on the edge of a cliff ( a favorite target for lightning) or standing up in the middle of a field far from any tall object-- but airports are full of tall objects that will attract lightning preferentially to the ramp area--